Trailers are well-known vehicle accessories used for transporting a variety of cargos. Trailers attach to a towing vehicle by means of a coupling assembly in the front of the trailer that attaches to a hitch assembly connected to the back of the towing vehicle. Trailers exert significant forces on the towing vehicle during transport. Due to the substantial danger of injury or of cargo or trailer damage if a trailer disconnects from the towing vehicle during transit, hitch assemblies are commonly mounted directly to the towing vehicle frame or built into the frame during manufacture.
Unfortunately, most trailers can only accommodate a very limited height differential before the coupling assembly becomes incapable of attaching to the hitch assembly. Most trailers are also incapable of attaching to different types of towing vehicles, as the fifth-wheel hitch assemblies for a semi-truck are very different from the pintle-ring hitch assemblies commonly found on agricultural, industrial, and military towing vehicles. As a result, cargo may need to be shifted from trailer to trailer to accommodate different towing vehicles, resulting in loss of time and increased manpower requirements. If additional trailers are not available, then the cargo cannot be moved at all. Furthermore, certain types of trailer may be manufactured with a coupling assembly for only one type of towing vehicle, making them unable to connect to other vehicles.
U.S. Pat. No. 3,918,744 to Gay discloses a vertically adjustable hitch assembly connecting a vehicle to a towing unit. The hitch assembly has a pair of parallel links pivotally connected to a towing connector and having an actuator for the braking system. However, Gay does not appear to disclose or suggest attachment via a fifth-wheel hitch assembly.
U.S. Pat. No. 4,433,853 to Swaim is directed to a convertible trailer hitch for towing a trailer, which includes a gooseneck arm for use as a hitch. The gooseneck arm is braced by an A-frame tongue and the hitch can be converted to a bumper type hitch by detaching the forward end of the tongue from the gooseneck arm, swinging the same down and attaching it to the rear of the towing vehicle. Swaim, too, does not appear to disclose or suggest attachment via a fifth-wheel hitch assembly, or attachment to any vehicle other than a pickup truck.
U.S. Pat. No. 8,398,109 to Amrine, Jr. and U.S. Pat. No. 8,210,557 to Schneider illustrate trailers which have three decks, including: 1st deck which is the trailer bed for receiving goods to be hauled; 2nd deck for attaching the trailer to the vehicle; and 3rd articulated deck which can raise or lower the 2nd deck depending on whether the attachment is via a trailer hitch or a kingpin. However, both Amrine and Schneider require raising and lowering multiple articulated decks, reducing the overall strength of the trailer.